Chaotic Law

I own a 2003 Chevy Tahoe and the battery died. I tried to start it and it almost
turned over but then the starter started clicking because the battery didnt
have enough power. Now several random things stopped working. The dash
gauges (Oil, temp, fuel and voltage only) stopped working. They all show
zero. The speedometer, tachometer and odometer still work. The small
indicator that shows what gear you are in stopped working. All the door locks
and window controls stopped working. None of the buttons on any of the
doors work any longer. Including the mirror control, power windows, power
door locks. I had my stereo shop check all the fuses and they are all fine. And
I had a load test done on the alternator and it checks out fine. The Auto parts
store does a free check engine light check and they could not get their
checker to communicate with the ECU. Anyone have any ideas?